Filtration material

Abstract

A high temperature resistant filtration material is produced having outer layers of a nonwoven fabric made of fibers of an aromatic polyamide having repeating units of the formula ##SPC1## A first inner layer of nonwoven fabric made of glass fibers and a second inner layer woven from yarns of glass or said aromatic polyamide. The fibers of the layers are interentangled by needling to form an integral structure.

We claim: 
     
       1. A high temperature resistant filtration material comprising: a. Two outer layers of nonwoven fabric of fibers of an aromatic polyamide having repeating units of the formula ##SPC3##   b. A first inner layer of nonwoven fabric of glass fibers, and   c. A second inner layer of woven fabric made of yarns of glass or said aromatic polyamide, said layers being needled together into an integral structure.     
     
     
       2. A filtration material as claimed in claim 1 wherein said fibers of an aromatic polyamide of said outer layer have a maximum denier of 5. 
     
     
       3. A filtration material as claimed in claim 1 wherein the glass fibers of said first inner layer have a maximum denier of about 5. 
     
     
       4. A high temperature resistant filtration material comprising: a. Two outer layers of nonwoven fabric of fibers which have a maximum denier of about 5 and are composed of an aromatic polyamide having repeating units of the formula ##SPC4##   b. A first inner layer of nonwoven fabric of glass fibers having a maximum denier of about 5, said layer having a weight of about 1 to 10 ozs./yd. 2     c. A second inner layer of woven fabric made of yarns of glass or said aromatic polyamide, said fabric having a weight of about 0.75 to 10 ozs./yd. 2   said layers being needled together into an integral structure.     
     
     
       5. A filtration material as claimed in claim 4 wherein said woven fabric is made of yarn containing continuous glass filaments. 
     
     
       6. A filtration material as claimed in claim 4 wherein said woven fabric is made of spun yarn containing fibers of said aromatic polyamide.